Field-induced Tomonaga-Luttinger liquid phase of a two-leg spin-1/2 ladder with strong leg interactions

TL;DR

This paper investigates the quantum phase transition in a spin-1/2 ladder compound under magnetic field, revealing a Tomonaga-Luttinger liquid phase characterized by linear specific heat at low temperatures, supported by experimental and theoretical agreement.

Contribution

It demonstrates that DIMPY is the first model material exhibiting a Tomonaga-Luttinger liquid phase in a strong-leg two-leg spin-1/2 ladder under magnetic field.

Findings

Observation of a field-induced gapless phase with linear specific heat.

Inelastic neutron scattering matches theoretical predictions.

DIMPY as the first strong-leg ladder material showing TLL behavior.

Abstract

We study the magnetic-field-induced quantum phase transition from a gapped quantum phase that has no magnetic long-range order into a gapless phase in the spin-1/2 ladder compound bis(2,3-dimethylpyridinium) tetrabromocuprate (DIMPY). At temperatures below about 1 K, the specific heat in the gapless phase attains an asymptotic linear temperature dependence, characteristic of a Tomonaga-Luttinger liquid. Inelastic neutron scattering and the specific heat measurements in both phases are in good agreement with theoretical calculations, demonstrating that DIMPY is the first model material for an S=1/2 two-leg spin ladder in the strong-leg regime.